Etch bleaching processes for making lithographic printing plates using silver halide and/or diffusion transfer layers and a hydrophilic layer

ABSTRACT

In a plate or light-sensitive plate for making printing plates comprising a support having an oleophilic surface carrying thereon a photosensitive silver halide emulsion layer, a hydrophilic diffusion transfer image receiving layer containing physical development nuclei, or both an image receiving layer and a photosensitive silver halide emulsion layer formed on the image receiving layer, the press life of a printing plate made from the plate is effectively improved by providing between the support and the lowermost layer a hydrophilic intermediate layer of, e.g., gum arabic, a maleic anhydride-vinyl acetate copolymer or a partially saponified cellulose derivative.

Kubotera et al.

ETCI-I BLEACI-IING PROCESSES FOR MAKING LITI-IOGRAPI-IIC PRINTING PLATESUSING SILVER HALIDE AND/OR DIFFUSION TRANSFER LAYERS AND A HYDROPI-IILICLAYER Inventors: Kikuo Kubotera; Eiichi Mizuki,

both of Saitama; Tadahiro Fujiwara; Nobuo Tsuji, both of Kanagawa, allof Japan Fuji Photo Film Co., Ltd., Minami-ashigara, Japan Filed: Feb.23, 1973 Appl. No 335,219

Assignee:

Foreign Application Priority Data Feb. 25, 1972 Japan 47-19922 US. Cl.96/29 L; 96/33 Int. Cl. G03C 5/54 Field of Search 96/29 L, 35.1, 33

References Cited UNITED STATES PATENTS 5/1968 Ormsbee 96/29 L Dec. 30,1975 3,552,315 1/1971 Ormsbee 96/76 3,557,696 1/1971 Ho0ver...' 96/763,567,442 3/1971 Land 96/76 3,690,883 9/1972 Hyland 96/29 L PrimaryExaminerCharles I... Bowers, Jr.

Assistant ExaminerJohn L. Goodrow Attorney, Agent, or FirmSughrue,Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT In a plate orlight-sensitive plate for making printing plates comprising a supporthaving an oleophilic surface carrying thereon a photosensitive silverhalide emulsion layer, a hydrophilic diffusion transfer image receivinglayer containing physical development nuclei, or both an image receivinglayer and a photosensitive silver halide emulsion layer formed on theimage receiving layer, the press life of a printing plate made from theplate is effectively improved by providing between the support and thelowermost layer a hydrophilic intermediate layer of, e.g., gum arabic, amaleic anhydride-vinyl acetate copolymer or a partially saponifiedcellulose derivative.

14' Claims, 7 Drawing Figures US. Patent Dec. 30, 1975 Sheet 1 0f 33,929,481

N? m n I5 25 22 VAWIIZI IJQE 2| 7 25 Q B NLNHQWz n 22 'IO 24 2;

I2 28 H H H 2 33 2o |9 m E 121 H W" 29 |r-| n g H/ZI 2O US Patent Dec.30, 1975 Sheet 2 of3 3,929,481

US. atent Dec. 30, 1975 Sheet 3 of3 3,929,481

ETCH BLEACIIING PROCESSESFOR MAKING LITHOGRAPHIC PRINTING PLATES USINGSILVER HALIDE AND/OR DIFFUSION TRANSFER LAYERS AND A HYDROPI-IILIC LAYERBACKGROUND OF THE INVENTION l. Field of the Invention The presentinvention relates to a plate or light-sensitive plate for makingprinting plates and more particularly it relates to a plate orlight-sensitive plate capable of providing a printing plate havingimproved printing life. The invention also relates to a lithographicprinting plate having improved press life.

2. Description of the Prior Art A lithographic printing plate isgenerally composed of an oleophilic ink-receptiveportion forming animaged portion anda hydrophilic portion forming a nonimaged portion. Asmethods of making such a lithographic printing plate there are known,e.g., a method in which a hydrophilic surface of a light-sensitive plateis converted into an oleophilic portion at only imaged portions and amethod in which a hydrophilic layer is formed on the surface of anoleophilic material and the hydrophilic layer is removed at only theimaged portions, exposing the oleophilic surface of the substrate.

One method belonging to the latter type is described in thespecification of Japanese Patent Publication No. 27,242/l969, whichteaches a method of making a printing plate by forming on a supporthaving an oleophilic surface a hydrophilic diffusion transfer imagereceiving layer containing nuclei for the diffusion transfer method,further applying thereto a photosensitive silver halide emulsion layerto provide a light-sensitive plate, forming a silver image in thehydrophilic layer by diffusion transfer development and removing,utilizing the silver ,image, the hydrophilic layer at the imaged portionby etching bleach processing to thereby expose the oleophilic surface ofthe support.

In. U.S. Pat. No. 3,385,701 there is described a method of making aprinting plate in which a sheet prepared by forming a hydrophilicdiffusion transfer image receiving layer containing nuclei for adiffusion transfer method directly on a support having an oleophilicsurface is brought into contact with an imageexposed negative and issubjected to diffusion transfer development to form a silver image inthe hydrophilic diffusion transfer image receiving layer. By utilizingthe silver image, the hydrophilic diffusion transfer image receivinglayer is removed at the imaged portions by an etching-bleach processingto thereby expose the oleophilic surface of the support.

Moreover, in Belgian Pat. No. 717,466 there is described a method ofmaking a printing plate in which a light-sensitive plate comprising asupport having thereon a non-porous hydrophilic layer having a contactangle of less than 65 and a light-sensitive silver halide emulsion layerhaving a melting point of lower than 82C. is image exposed and developedto form a positivesilver image in the emulsion layer, and then the plateis subjected to etching-bleach processing to etch the emulsion layer atthe silver image portion and to expose the surface of the hydrophiliclayer, whereby a printing plate having a hydrophilic surface at theimaged portions and an oleophilic emulsion layer at the non-imagedportions is obtained.

However, those known printing plates have various faults, e.g., whenprinting is conducted using those by the strippingof the hydrophiliclayer(s) and thus it is difficult to obtain many prints having goodquality using those printing plates. For instance, in the printing platedisclosed in the specification of Japanese Patent Publication No.27,242/1969, a hydrophilic diffusion transfer image receiving layer isdirectly formed on the oleophilic surface of a support and thus theadhesive property between the support surface and the hydrophilicdiffusion transfer image receiving layer is insufficient, whichfrequently results in stripping of the hydrophilic diffusion transferimage receiving layer at nonimaged portions during printing, thuscausing stains by the adhesion of an oily ink thereto.

In an ordinary lithographic printing plate which is composed of anoleophilic surface and a hydrophilic diffusion transfer image receivinglayer formed directly thereon, which utilizes the difference in affinityfor an oily ink between the oleophilic surface exposed by removing thehydrophilic diffusion transfer image receiving layer at the imagedportions and the remaining hydrophilic layer, it is necessary to preventthe formation of stains caused by the adhesion of ink to the nonimagedportions by making the difference in affinity for the ink as large aspossible. This can be attained by increasing the hydrophilicity of thehydrophilic layer. However, an increase in the hydrophilicity results inreducing the adhesive property between the oleophilic surface and thehydrophilic layer and causes stripping of the hydrophilic layer itselfat non-imaged portions during printing which results in the formation ofstains. Therefore, it has long been desired in this field of art toovercome the defects mentioned above and to provide printing plateshaving a large printing capacity.

SUMMARY OF THE INVENTION One object of this invention is, therefore, toprovide a plate or light-sensitive plate for making a printing platecapable of giving a large number of printings without causing stains.

Another object of this invention is to provide a method of printingwhich gives more than several thousand stable prints without causingstains using an etching-bleach process.

Still another object of this invention is to provide a plate orlight-sensitive plate for direct printing capable of providing dotimages directly from an original using a highly sensitive silver halidelight-sensitive material for giving a large number of prints from theoriginal, the light-sensitive plate after forming dot images being usedas a direct lithographic printing plate capable of giving halftoneprints having good quality and a high light portion of good fine dotreproduction.

Still another object of this invention is to provide a light-sensitivematerial for photographic direct printing plates capable of being usedas a line work printing plate.

Other objects of this invention will be understood from the followingdescription.

These objects of the invention can be attained by using a plate orlight-sensitive plate for making a printing plate comprising anoleophilic support carrying thereon a photosensitive silver halideemulsion layer anda hydrophilic diffusion transfer image receiving layercontaining physical development nuclei (this layer is hereinafter calleda silver image forming layer), or a silver image forming layer and aphotosensitive silver halide emulsion layer wherein a hydrophilic 7 3 vintermediate layer is formed between the support and the-lowermost layerdescribed above by applying to the surface of the olephilic support,prior to forming the aforesaid silver halide emulsion layer or thesilver image forming layer, an organic solvent solution of a hydrophilicresin, a resin which can be modified so as to be hydrophilic uponcontact with the alkali in a developer, an oleophilic'resin whichbecomes porous and hydrophilic by brushing, or a mixture of such resins,followed by removing the organic solvent.

The light-sensitive plate is exposed behind an original and developed toform a positive silver image in the silver image forming layer(s). Theplate is then etchbleached in an acid solution containing cupricchloride and aoxidizing agent such as hydrogen peroxide to bleach thedeveloped silver and at the same time to etch'away both the silver imageforming layer carrying the developed silver image and the hydrophilicintermediate layer under the silver image portion, whereby theoleophilic surface of the support is exposed at that portion and thus aprinting surface having excellent printabilityis obtained. 'Theimportant feature of this invention in this case is that the thinhydrophilic intermediate layer formed under the silver image forminglayer is etched away at portions corresponding to the silver image ofthe silver image forming layer by the etch-bleach treatment togetherwith the silver image forming layer to expose the oleophilic surface ofthe support and to provide an excellent printing surface.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 7 show variousembodiments of producing printing plates in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION The above-described phenomononobtained using the light-sensitive material or plate for a printingplate has not hitherto been known and is an important feature of thisinvention, that is to say, the present invention is based on the newdiscovery that etching can be diffusion transferred.

An mentioned before, according to the inventions described in JapanesePatent Publication No. 27242/1969 and US. Pat. No. 3,385,701, ahydrophilic diffusion transfer image receiving layer or a photosensitivesilver halide emulsion layer is directly formed on the oleophilicsurface of a support, a silver image is formed in the image receivinglayer or the silver halide emulsion layer, the image receiving layer orthe silver halide emulsion layer is removed at the silver image portionsto thereby expose the oleophilic surface of the support and to thusprovide a printing surface. Further, in the specification of BelgianPatent No. 717,466 there is described an example in which a hydrophiliclayer formed under a silver image forming layer is not etched, that is,according to this Belgian patent a lightsensitive material for aprinting plate prepared by forming a hardened gelatin layer containingtitanium dioxide on the surface of an aluminum plate which had beenanodically oxidized in a phosphoric acid bath, and further applyingthereto a hardenable silver chloride emulsion, is exposed, developed andthen bleached for 60 seconds in a solution having the followingcomposition.

Cupric chloride g g -continued Citic acid g Thiourea 75 g Watercontaining l5/ 1000 of hydrogen peroxide solution 1 liter.

The plate is then washed with water to remove the etched silver halideemulsion layer and to provide a printing surface. By this method,however, ink will adhere to the subbing layer, i.e. since the hardenedgelatin layer formed under the silver halide emulsion layer remainswithout being etched away, ink adhereas to the layer to cause stains.Thus, the Belgian patent describes an example of forming apolyacrylamide layer in place of the gelatin subbing layer in Example 2of the Belgian patent, and by using the light-sensitive plate having thepolyacrylamide subbing layer, a printing plate is produced by the samemanner as in Example l of the same patent. In this case, the hydrophilicsurface of the polyacrylamide layer formed under the silver halideemulsion layer remains without being removed by the etching treatmentand is exposed by the etching treatment. Thus, the exposed surface ofthe polyacrylamide subbing layer is utilized as a hydrophilic printingsurface and the remaining silver halide emulsion layer is utilized as anoleophilic imageforming surface. i

As mentioned above, in the conventional techniques disclosed aslithographic printing methods wherein silver images are etched in anetch-bleach bath to provide printing surfaces with a difference ininkreceptive power, only the colloid layer or emulsion layer having asilver image is removed by etching, and a hydrophilic layer formed underthe colloid layer or the emulsion layer remains without being etchedaway and is utilized as it is as the printing surface.

On the other hand, we have discovered, in this invention, theastonishing new fact that etching at the portion of a silver imageforming layer carrying a silver image works upon a subbing layer andhave succeeded in-making an excellent printing plate or surface.

In more detail, the inventionrelates to a light-sensitive material formaking a printing plate comprising a support having an oleophilicsurface carrying thereon a photosensitive silver halide emulsion layer,a material for making a printing plate comprising a support having anoleophilic surface carrying thereon a hydrophilic diffusion transferimage receiving layer containing physical development nuclei, or alight-sensitive material for making a printing plate comprising asupport having an oleophilic surface carrying thereon a photosensitivesilver halide emulsion layer and. a hydrophilic diffusion transfer imagereceiving layer containing physical development nuclei or carryingthereon the hydrophilic diffusion transfer image receiving layer asabove and a photosensitive silver halide emulsion layer, characterizedin that a hydrophilic intermediate layer is formed between the supportand the lowermost layer. The invention also relates to a method ofproducing a printing plate from such a light-sensitive material ormaterial for making a printing plate.

We discovered, as disclosed in our prior application, Japanese PatentPublication No. 2283,/197 4, a similar light-sensitive material formaking printing plate having a thin gelatin or nitrocellulose layer asthe hydrophilic intermediate layer which is positioned between a supportand a lowermost layer and is also etched away by etch-bleach treatmentat a silver image portion. In the present invention, however, we havefurther discovered that an excellent light-sensitive material forprinting plates the same as or superior to those of our priorapplication can also be obtained using specific compounds other thangelatin or nitrocellulose as the material for the intermediate layer.

As the materials or light-sensitive materials of this invention formaking printing plates, there are many embodiments, which will beexplained in detail by referring to the accompanying drawings, in whichFIG. 1 to FIG. 7 show typical embodiments of our invention eachincluding a materials for making a printing plate and the manner ofmaking a printing plate.

FIG. 1 is schematic view showing an embodiment of our invention. FIG. LAis a sectional view showing the light-sensitive material of thisinvention for making a printing plate composed of a support 10 having anoleophilic surface, a hydrophilic intermediate layer 11 which can beetched away at the portion corresponding to a silver image formed in asilver halide emulsion layer, and an unhardened silver halide emulsionlayer 12. FIGS. l-B to l-E are cross sectional views of the material ofthis invention in the main stages of making a printing plate by anembodiment of the method of this invention. In the stage shown in FIG.l-B, the light-sensitive material 13 for making a printing plate isexposed through a negative original 15 having continuous tone behind acontact screen 14. A dot latent image 16 is formed in this stage fromthe continuous tone original by the contact screen. The stage of FIG.l-C shows the state when the plate is developed in a lithographicdeveloper, whereby the latent image 16 at the exposed portion of theemulsion layer 12 is developed to form a silver image 17. This silverimage has the opposite gradation to that of the original, in otherwords, because the original is negative in this case, the silver imageformed is positive. After development, the plate may be fixed, butusually the fixing step is omitted. After rinsing, the plate thusdeveloped is treated in an etch-bleach solution, and thus the portion ofthe silver halide emulsion layer having the silver image is etched. Thisstate is shown in the state of FIG. l-D, in the case of which thehydrophilic intermediate layer 11 under the silver halide emulsion layer12 has been affected by the etching action at the portions correspondingto the silver image.

When the plate surface is rubbed with a sponge in a warm water bath atabout 30C., the hydrophilic intermediate layer 11 is removed at theportion affected by the etching action together with the silver halideemulsion layer 12. This state is shown in the stage of FIG. l-E. Thus,the hydrophilic intermediate layer 11 is removed at the portioncorresponding to the image portion to expose the surface 18 of theoleophilic support 10 providing an image yielding portion at printing,while the hydrophilic intermediate layer 11 remains at the portion 19corresponding to the non-imaged portions providing a non-imaged yieldingportion at printing. The printing plate thus prepared can be used by anordinary printing method.

FIG. 2 is schematic views showing a second embodiment of our invention.In FIG. 2-A is shown a sectional view of an embodiment of thelight-sensitive material of this invention for making a printing platecomposed of a support 20 having an oleophilic surface, a hydrophilicintermediate layer 21 to be etch-bleached at the portions correspondingto a silver image formed in a silver halide emulsion layer, a negativeemulsion stripping layer 22 and a hardenable silver halide emulsionlayer 23.

FIG. 2-B to FIG. 2-E are schematic views showing the stages of making aprinting plate using the light-sensitive material shown in FIG. l-Aaccording to an embodiment of the method of this invention.

In the stage shown in FIG. 2-B, the light-sensitive material 24 formaking a printing plate is exposed through a negative continuous toneoriginal 26 behind a contact screen 25. In this stage, a dot latentimage 27 is formed in the silver halide emulsion layer 23 of thelight-sensitivematerial 24 from the continuous tone original by thecontact screen. The plate thus exposed is developed in a lithographicdeveloper and this state is shown in FIG. 2-C, in the case of which asilver image 28 is formed in the silver halide emulsion layer at theportion having the latent image 27. The plate is then treated in anetch-bleach solution, whereby the silver halide emulsion layer 23 isetched at the imaged portion and also the stripping layer 22 and thehydrophilic intermediate layer 21 are affected by the etching action.This state is shown in FIG. 2-1).

When the plate surface is rubbed by a sponge in a warm water bath at30C. the hydrophilic intermediate layer is removed at portions affectedby the etching action together with the silver halide emulsion layer 23and the stripping layer 22. This state is shown in FIG. 2-E. In thisstage, the hydrophilic intermediate layer 21 is removed at the portioncorresponding to the image portions of thesilver halide emulsion layertothereby expose the surface 29 of the oleophilic support 20, while thehydrophilic intermediate layer 21 remains at the portion correspondingto the non-imaged portions. The printing plate thus prepared can be usedin a conventional manner.

Each of the embodiments explained above is a negative process or aprocess of forming a printing plate of the type where ink adheres to theexposed portions of the light-sensitive material.

The case of applying our invention to a positive process or a process ofpreparing a printing plate of the type where ink adheres at portionscorresponding to the unexposed portions of the light sensitive materialwill be described by the following embodiments.

FIG. 3 is schematic views showing a third embodiment of our invention.FIG. 3-A is a cross sectional view showing an embodiment of thelight-sensitive material of this invention for making a printing platecomposed of a support 30 having an oleophilic surface, a hydrophilicintermediate layer 31 which can be etched at the portions correspondingto the silver image formed in a silver halide emulsion layer, and anunhardenable silver halide emulsion layer 32 of the direct positivetype.

FIG. 3-B to FIG. 3-D are schematic views showing the stages of preparinga printing plate using the lightsensitive plate shown in FIG. 3-Aaccording to one embodiment of the method of this invention.

In FIG. 3-B, the light-sensitive plate 33 of this invention is exposedthrough a positive original 34 having a dot or line image, and a latentimage 32 is formed in the silver halide emulsion layer 33 at thenon-imaged portions. The plate is then developed in an ordinarydeveloper, and this stage is shown in FIG. 3-C. In this stage a silverimage is formed in the silver halide emulsion layer 32 at unexposedportions. After development, the plate may be fixed, but usually thefixing step is omitted. After rinsing, the plate is treated in a knownetchbleach solution, whereby the portion of the silver halide emulsionlayer having the silver image is etched and in this case the hydrophilicintermediate layer 31 under the silver halide emulsion layer is affectedby the etching action at portions corresponding to the silver image.Then, when the plate surface is lightly rubbed with a sponge in a warmbath at about 30C., the silver halide emulsion layer and the hydrophilicintermediate layer at the portions affected by the etching action areremoved. This state is shown in FIG. 3-E, in which the silver halideemulsion layer has been removed together with the hydrophilicintermediate layer thereunder at portions corresponding to the silverimage to thereby expose the oleophilic surface of the support, while thehydrophilic intermediate layer remains at the nonimaged portions. Theprinting plate thus made can be used in a conventional manner.

FIG. 4 shows schematic views of a fourth embodiment of our invention.That is to say, FIG. 4-A is a sectional view showing an example of thelight-sensitive material for making a printing plate composed of asupport 40 having an oleophilic surface, a hydrophilic intermediatelayer 41 which can be etched at portions corresponding to a silver imageformed in a silver halide emulsion layer, a negative emulsion strippinglayer 42, and a hardenable silver halide emulsion layer of the directpositive type 43.

FIG. 4-B to FIG. 4-E are schematic views showing the stages of making aprinting plate using the light-sensitive plate shown in FIG. 4-Aaccording to an embodiment of the method of this invention.

In the stage of FIG. 4-B, the light-sensitive plate 44 of this inventionis exposed through a positive original 45 and in this stage there isformed a latent image 46 in the emulsion layer 45 of the light-sensitiveplate 44 at the exposed portions, i.e., the portions corresponding tothe non-image portions of the original. The plate is then developed,whereby a silver image is formed in the silver halide emulsion layer 43at the portions corresponding to the image portions of the original.This state is shown in FIG. 4-C.

After rinsing, the plate is treated in a conventional etch-bleachsolution, whereby the silver halide emulsion layer is etched at theportion having the silver image and in this case both the strippinglayer 42 under the silver halide emulsion layer and the hydrophilicintermediate layer 41 are affected by the etching action. This state isshown in FIG.'4-D. When the surface of the plate is lightly rubbed witha sponge in a warm water bath at about 30C. the silver halide emulsionlayer 43 and the stripping layer 42 are removed together with thehydrophilic intermediate layer 41 at the portions affected by theetching action. This state is shown in FIG. 4-E, in which the silverhalide emulsion layer and the stripping layer have been removed togetherwith the hydrophilic intermediate layer at the non-image portions tothereby expose the oleophilic surface of the support 47, while thehydrophilic intermediate layer 48 remains at the non-image portions. Theprinting plate thus made can be used according to a conventional manner.

FIG. is schematic views of a fifth embodiment of this invention formaking a printing plate. FIG. 5-A is a sectional view of an example ofthe light-sensitive plate of this invention for making printing platecomposed of a support 50 having an oleophilic surface, a hydrophilicintermediate layer 51, and a hydrophilic diffusion transferimage-receiving layer 52 containing physical development nuclei.

FIG. S-B to FIG. 5-D are schematic views showing the stages of making aprinting plate using the light-sensitive plate of FIG. 5-A according toan embodiment of the method of this invention.

In FIG. S-B, the plate 55 of this invention having the above-mentionedstructure and a light-sensitive material 56 composed of a support 54,such as a paper or a plastic film, and a photosensitive silver halideemulsion layer 53 formed thereon are shown.

In the light-sensitive material 56, a latent image 53a has beenpreliminaraly formed by exposure at portions of the photosensitivesilver halide emulsion layer corresponding to the non-image portions ofan original. The light-sensitive material 56 is placed on the plate 55for a printing plate with a diffusion transfer photographic developerbetween them to conduct the development. This state is shown in FIG.S-C, and in this stage the silver halide in the exposed portion, i.e.,the latent image portion of the silver halide emulsion layer 53, ischemically developed to form a silver image therein. The silver imagethus formed is negative to the original image. On the other hand, in theimage receiving layer 52 of the plate 55 there is formed a silver imageat the portions corresponding to the image portion of the originalbecause the silver halide in the silver halide emulsion layer 53 at theunexposed portions diffuses as a complex salt into the image receivinglayer 52 by the action of a solvent for silver halides contained in thedeveloper, whereby the complex salt of a silver halide is brought intocontact with the physical development nuclei present in the imagereceiving layer to be reduced into metallic silver and to form asilv'erimage therein. This silver image formed in the image receivinglayer is positive to the original.

After development, the plate 55 is separated from the light-sensitivematerial 56 and, after rinsing, the plate is treated in a conventionaletch-bleach solution. By this treatment the image receiving layer isetched at the portions having the silver image. In this case, thehydrophilic intermediate layer 51 under the image receiving layer isaffected by etching action at the portion corresponding to the silverimage portion of the image receiving layer. Then, when the surface ofthe plate is lightly rubbed with a cotton pad, the image receiving layerand the hydrophilic intermediate layer are removed at the etchedportions to expose the oleophilic surface of the support 50. On theother hand, the hydrophilic image receiving layer of the nonimagedportion remains together with the hydrophilic intermediate layer underthe non-imaged portion of the image receiving layer. This state is shownin FIG. S-D.

The printing plate thus formed can provide many stable duplicationshaving high image quality using commercially available printing inks andwetting water.

In the embodiment shown in FIG. 5, the plate for making a printing plateis separated from the light-sensitive material and thus the plate can becombined, at use, with any desired light-sensitive material, ifnecessary. Also, the plate for making a printing plate is itselfnon-light sensitive, and thus the preservation and handling of such aplate are quite simple.

Now, if it is possible to form an image on a light-sensitive materialfrom an original and to make a printing plate therefrom using a simpleprocedure, such a system is economically attractive and is also laborsaving. Both of these objects are met by combining a light-sensitivematerial and a plate for a printing plate according to the presentinvention, as illustrated by the embodiments shown in FIG. 6 and FIG. 7.

FIG. 6 shows a sixth embodiment of our invention. FIG. 6-A is a crosssectional view of the light-sensitive plate for a printing plate of thisinvention composed of a support 60 having an oleophilic surface, ahydrophilic intermediate layer 61, a hydrophilic diffusion transferimage receiving layer 62 containing physical development nuclei, and anon-hardenable photosensitive silver halide emulsion layer 63. FIG. 6-Bto FIG. 6-F are schematic views showing the stages of making a printingplate by the sixth embodiment of this invention using thelight-sensitive plate shown in FIG. 6-A.

In FIG. 6-B is a cross sectional view showing exposing thelight-sensitive plate 64 of this invention through a positive original65. In this stage there is formed a latent image 66 in the silver halideemulsion layer 63 of the light-sensitive plate 64 at the positionscorresponding to the non-image portions of the original 65. This latentimage is negative to the original.

FIG. 6-C shows the state where the light-sensitive plate thus exposed issubjected to a diffusion transfer development, whereby the silver halidein the exposed portions 66 of the silver halide emulsion layer 63 ischemically developed form a silver image. On the other hand, in theimage receiving layer 62 there is formed a silver image at the portioncorresponding to the nonexposed portions of the emulsion layer 62. Thesilver image of the image receiving layer 62'is formed due to thephenomenon that the silver halide in the nonexposed portions of thesilver halide emulsion layer 63 is diffused as a complex salt thereofinto the image receiving layer 62 by a solvent for silver halidescontained in the developer, is brought into contact with the physicaldevelopement nuclei in the image receiving layer and is there reducedinto metallic silver. This silver image is positive to the original,i.e'., is the same image as the original.

The plate for a printing plate thus developed is immersed in a warm bathat about C., where the silver halide emulsion layer is removed. Thisstate is shown in FIG. 6-D.

The plate having the positive silver image in the image receiving layer62 is treated in an etch-bleach solution containing hydrogen peroxide.By this treatment, the portion of the image receiving layer 62 havingthe silver image is etched and at the same time the portions of thehydrophilic intermediate layer 61 under the silver image portion of theimage receiving layer 62 are also etched. This state is shown in FIG.6-E.

By rubbing weakly the surface of the plate thus subjected to theetch-bleach treatment, the etched portions of the both layers areremoved and the oleophilic surface of the support 60 is exposed. Thisstate is shown in FIG. 6-F.

The printing plate thus prepared can provide many prints havingexcellent image quality.

FIG. 7 shows schematic views of a seventh embodiment of this invention.

FIG. 7-A is a cross sectional view of the light-sensitive plate for aprinting plate of this invention composed of a support 70 having anoleophilic surface, a hydrophilic intermediate layer 71 formed thereon,a hydrophilic diffusion transfer image receiving layer 72 containingphysical development nuclei, a stripping layer 73 for negative emulsionlayerand a hardenable photosensitive silver halide emulsion layer 74.

FIG. 7-B to FIG. 7-F are schematic views showing the stages of making aprinting plate by the seventh embodiment of this invention using thelight-sensitive plate shown in FIG. 7-A.

FIG. 7-B' is a sectional view of the state of exposing thelight-sensitive plate 75 of this invention through a positive original76. In this stage there is formed a latent image 77 at the portions ofthe silver halide emulsion layer 74 corresponding to the non-imageportions of the original. This latent image is negative to the original.

FIG. 7-C shows the state where the plate thus exposed is subjected to adiffusion transfer development, whereby the silver halide in the exposedportion of the silver halide emulsion layer 74 is chemically developedto form a silver image. On the other hand, in the image receiving layer72 there is also formed a silver image at the portions corresponding tothe nonexposed portions of the silver halide emulsion layer 74. Thesilver image in the image receiving layer 72 has been formed by thephenomenon that the silver halidein the non-exposed portions of thesilver halide emulsion layer is diffused as .a complex salt thereofthrough the stripping layer 73 into the image receiving layer 72,brought into contact with the physical development nuclei'in the imagereceiving layer 72, and reduced into metallic silver. The silver imageis positive to the original.

The plate thus developed is immersed in a warm water bath at about 30C.to remove the emulsion layer. This state is shown in FIG. 7-D. Then, theplate having the positive silver image is treated in an etchbleachsolution containing hydrogen peroxide and by this treatment the portionsof the image receiving layer having the silver image are etched and atthe same time the portions of the hydrophilic intermediate portion underthe silver image portion of the image receiving layer are etched andbecome readily removable. This state is shown in FIG. 7-E. I

Then, by weakly rubbing the surface of the plate thus subjected to theetch-bleach treatment with a cotton pad, the etched portions are removedto expose the oleophilic surface of the support 70, while thehydrophilic image receiving layer remains on the support at thenon-image portions together with the intermediate layer under theseportion. This state is shown in FIG. 7-F.

The printing plate thus prepared can provide many prints havingexcellent image quality by using commercially available printing ink andwetting water.

In the practice of this invention it is a necessary factor for improvingthe press life of the printing plate made from the plate orlight-sensitive plate of this invention that the hydrophilicintermediate layer be strongly adhered to the oleophilic surface of thesupport.

The reason that the hydrophilic intermediate layer must be stronglybonded to the oleophilic surface of a support in our invention isconsidered to be as follows, although the following theory is not alwaysdefinitive. By selectively employing a definite material for thehydrophilic intermediate layer and a definite organic solvent thereforin accordance with the present invention, a co-fusion of the material ofthe intermediate layer and the support is caused at the interface ofboth layers, which results in a strong adherance of the hydrophilicintermediate layer to the oleophilic surface of the support. Thus, theprinting plate made using the plate or the light-sensitive plate ofthis'invention has an 11 1 improved press life. This feature is alsoimportant factor of this invention. On the other hand, a conventionalplate for making printing plate is produced by forming a coatingcomposition on the oleophilic surface of a support using water as thesolvent, and thus the adhesion between both layers is weak, stains areapt to form caused by stripping of. the hydrophilic layer at printingand the press life of the printing plate is poor.

. The hydrophilic intermediate layer used in this invention is selectedfrom the materials satisfying three factors: the hydrophilicintermediate layer adheres strongly to the oleophilic surface of asupport; the hydrophilic intermediate layer provides a good hydrophilicprinting surface at printing; and the. hydrophilicintermediate layermust be etched in the etch-bleach treatment at portions corresponding tothe silver image-containing portions of the layer above the intermediatelayer.

Known materials usually used in the field of photography as subbingmaterials may be used as materials for the hydrophilic intermediatelayer if they meet the above three factors. However, as is well known,materials used as a subbing layer must be selected from those satisfyingthe requirement that they have a strong adhesive property to both thesurface of a silver halide emulsion layer which is formed from anaqueous emulsion and the surface of a hydrophobic support, such as apolyester film or a cellulose acetate film, both of which have differentproperties.

The hydrophilic intermediate layer in this invention isrequired to havea strong adhesion to the oleophilic surface of a support and aproperadhesive property to the ,gelatino-silver halide emulsion layer formedthereon since the silver halide emulsion layer must be stripped away,after the etch-bleach treatment. Therefore, in the practice of thisinvention it is not necessary to select materials for the hydrophilicintermediate layer based solely upon the conventional concept of,subbing materials regarding adhesive property and the-materials may beselected from a broader range. However, itis most important to selectmaterials so that the hydrophilic intermediate layer made from thematerials are etched at portions corresponding to the silver imagecontaining portion of the layer above it in the case; of etch-bleachingthe silver image portion of the above layer and further the non-imagedportions of the intermediate layer remaining on the support must give agood hydrophilic printing face. This point is also one of the importantfeaturesof this invention.

As the materials for the hydrophilic intermediate layers in thisinvention, there may used hydrophilic resins, resins which will bemodified into hydrophilic resins by contact with an alkaline developer,and resins which are endowed with a hydrophilic property by the porositythereof, and these may be used alone or as a mixture thereof. Thehydrophilic resins of the present invention serve a superior protectivecolloid function, have good light transparency, superior permeability incontact with an alkaline developer and mixed easily in greatly varyingproportions with gelatin.

The resins to be used as the materials for the hydrophilic intermediatelayers inthis invention are shown below:

Group A: (hydrophilic resins) gum arabic, alginic acid, hydroxyethylcellulose, methyl cellulose, carboxymethyl cellulose, polyacrylamide,polyvinyl pyrrolidone, copolymers of the above compounds; polyvinylalcohol, and polyvinyl alcohol derivatives;

' Group B: maleic'anhydride-vinyl acetate copolymers, maleicanhydride-ethylene copolymers, maleic anhydride-methylvinyl ethercopolymers, maleic anhydridestyrene copolymers, half ester derivativesof those copolymers, acrylic acid copolymers, and methacrylic acidcopolymers;

Group C: partially saponified cellulose acetate, partially saponifiedcellulose butyrate and partially saponified cellulose acetate butyrate'The compounds of Group A, Group B, and Group C may be used alone or as amixture thereof.

While any of the above hydrophilic resins can be used in the presentinvention if they illustratethe general superior characteristics heretorecited, and the selection of any one specific hydrophilic resin is notoverly limited, nonetheless certain preferred materials do exist, whichare described below. 1

' Group A: polyvinyl pyrrolidone having an average molecular weight ofgenerally from 1,000 to 400,000, preferably 4,000 to 360,000;polyacrylamide having an average molecular weight of from 100,000 to1,500,000, preferably 500,000 to 1,000,000; hydroxyethyl cellulosehaving an average molecular weight of from 50,000 to 300,000; methylcellulose having an average molecular weight from 50,000 to 500,000;carboxymethyl cellulose having an average molecular weight of from50,000 to 500,000; polyvinyl alcohol or derivatives thereof having adegree of saponification of from 50 to preferably 60 to 99% and anaverage degree of polymerization of 300 to 5,000, preferably 500 to2,000; copolymers of polyvinylpyrrolidone and polyacrylamide have acopolymerization ratio on the order of one having a molecular weight of100,000 to 500,000.

Group B: copolymers of maleic acid anhydride vinyl acetate, maleic acidanhydride ethylene and maleic acid anhydridemethyl vinyl ether having acopolymerization ratio on the order of 1:1, copolymers of maleic acidanhydride-styrene having a copolymerization ratio less than 1:1,preferably 1:1 to 1:3; half-ester derivatives of the above materialssuch as meleic acid anhydride and methyl, ethyl, propyl, etc.,half-esters where the degree of esterification is 30 to 50%; acrylicacid copolymers with, for example, N-vinyl pyrrolidone, acrylamide,methacrylic acid, methacrylic amidevinyl acetate, diethyl acrylamide,and the like, the copolymerization ratio being freely variable but mostpreferably on the order of 1:1; copolymers of methacrylic acid with, forexample, acrylamide, diethyl acrylamide, vinyl pyrrolidone, methylacrylate, butyl methacrylate, propyl,.methyl acrylate,methylmethacrylate, ethylacrylate and the like, using a copolymerizationratio as desired, preferably on the order of 1:1.

Group C: preferred are those materials where the degree ofsaponification is less than 50%, preferably 0 to 30%.

In general, a hydrophilic layeris formed by dissolving or dispersinggelatin, nitrocellulose, a mixture of gelatin and nitrocellulose, or acopolymer of maleic anhydride and vinyl acetate in' an organic solventand applying the solution or the dispersion onto a support in anordinary manner. followed by drying to remove, the organic solvent.However, using the compounds of Group A, Group B, or Group C a plate orlight-sensitive plate for making a printing. plate showing excellentprintability the same as or superior to that of the case of usinggelatin, nitrocellulose, etc., as above is obtained.

The organic solvent used for coating the above-mentioned material is onewhich has the capability to swell, soften or dissolve the surface of thesupport. Practical examples of such an organic solvent are acetone,methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, methanol,ethanol, ethyl formate, methyl acetate, benzene, toluene, methylenechloride, ethylene chloride, tetrachloroethane, trichloroethane,chloroform, chlorobenzene, ethylene chlorohydrin, chlorosulfonic acid,nitromethane, dimethylformamide, morpholine, formic acid, acetic acid,benzoic acid, salicylic acid, salicylic acid esters, monochloroaceticacid, dichloroacetic acid, trichloracetic acid, trifluoroacetic acid,Z-nitropropanol, benzyl alcohol, benzamide, benzonitrile, benzylamine,methyl nicotinate, phenol, ochlorophenol, cresol, a divalent phenol suchas resorcinol and other phenol derivatives.

Those organic solvents may be used alone or as mixtures thereof.

The water content in the organic solvent varies depending upon thenature of the hydrophilic polymer used for the hydrophilic intermediatelayer, and the water acts as an aid for dispersing or dissolving thepolymer in the organic solvent. The essential mechanism involved is thatfirst the hydrophilic polymer is dissolved in the water, and then thepolymer (actually a hydrous solution thereof) diffuses into the organicsolvent. However, because the adhesion between the oleophilic surface ofthe support and the hydrophilic polymer is influenced by the watercontent in the organic solvent, it is preferred, for strongly adheringthe hydrophilic polymer layer to the surface of the oleophilic support,that the water content be as small as possible. Furthermore, ifnecessary, an additive for improving the coating property, anantihalation dye, or a developing agent may be dissolved or dispersed inthe coating composition or emulsion comprising the aforesaid polymer andthe organic solvent.

It is very important for obtaining the hydrophilic intermediate layereffective for the present invention to select and suitably control thecomposition of the material for forming the intermediate layer and thehardenability and the thickness of the layer. Moreover, the abovefactors are also influenced by the composition, hardenability andthickness of the silver image forming layer(s) formed over thehydrophilic intermediate layer, and also the amount of total silverformed by the development and the form of silver.

In general, the thickness of the hydrophilic intermediate layer is from0.1 micron to 3 microns, preferably from 0.2 micron to L5 microns.

Discussing some of the factors mentioned above in greater detail, andthe relationship of various layers, the hardenability of the hydrophilicintermediate layer must be such that it can be etched by means of anetch-bleach bath because when the emulsion layer is peeled off at about40C the hydrophilic intermediate layer is not dissolved.

The hydrophilic diffusion transfer image receiving layer containingphysical development nuclei will generally have a thickness of fromabout 0.1 to about 3 microns, preferably 0.2 to 1.5 microns. The layershould not be so thick that during etching the facing portions of thehydrophilic intermediate layer are not etched, and on the other hand thelayer should not be so hard that the layer is insufficiently etchedduring the etching treatment. If the above faults are encountered, thelayer cannot be used as a lithographic plate because the hydropholicsupport will not be exposed. It is generally sufficient if the amount-ofsilver formed in this layer is greater than 0.3 (optical concentration).

The silver halide emulsion layer which can be used instead of or inaddition to the hydrophilic diffusion transfer image receiving layer isgenerally about 1 to about 15 microns thick, more preferably 2 to 8microns thick. The weight ratio of silver halide/binder can vary greatlybut normally is in the range of 1/4 to 6/1 more preferably l/ 1 to 4/1.Generally speaking, better results are achieved at higher silverconcentrations, and the amount of silver will usually be 5 to 60 mg/dmpreferably l0 30 mg/dm In this regard, it is appropriate to mention thatthe hydrophilic, diffusion transfer image receiving layer containingphysical development nuclei merely need contain sufficient nuclei topermit an etchable image to be formed. The exact amount of physicaldevelopment nuclei can vary greatly, but generally speaking the weightratio of nuclei/binder is usually from about 0.1/l to about 0.001/1, thetotal nuclei content being at least about 0.001 mg/dm.

By forming the hydrophilic intermediate layer on the surface of asupport according to the present invention, the adhesive propertybetween the layer and the oleophilic surface of the support isstrengthened and the strength of the hydrophilic intermediate layer canbe increased, whereby the press life of the printing plate prepared fromthe light-sensitive plate having such a hydrophilic intermediate layercan be greatly increased and also the printing operation can beconducted quite stably by using the printing plate. However, thefollowing fault has to be overcome, that is, in order-to expose theoleophilic surface of the support at the desired portions, thehydrophilic intermediate layer formed on the support must be effectivelyetched at the portions corresponding to the silver image portions formedin the adjacent layer over the intermediate layer in the etch-bleachtreatment. Thus, according to the present invention, there is provided aplate or light-sensitive plate for making a printing plate in which thehydrophilic intermediate layer can be easily removed and the oleophilicsurface of the support is exposed by'an etchbleach treatment asindicated above, i.e., the properties required for the hydrophilicintermediate layer, the image forming layer or the stripping layer canbeattained by properly controlling the composition,-hardenability, andthickness of those layers and also the total amount of silver formed inthe image forming layer and the ratio of the amount of silver to themedium in the layer.

Other elements of the plate for printing plate of this invention, suchas the support, image-receiving layer, etc., can be formed using knowncompositions. As the support, there can be illustrated polymer filmssuch as polyethylene terephthalate, cellulose acetate, synthetic papers,water proof papers, metallic sheets, and the like. When a hydrophilicmetallic support such as an aluminum support is used, an oleophiliclayer is formed on'the surface of the support by coating, vacuumevaporation, plating, spray painting, laminating, etc. A polyethyeleneterephthalate film is frequently used since it has an excellentoleophilic property and excellent dimensional stability and flexibility.

Further illustrative of the many different types of resins which can beused as supports in accordance with the present invention arepolystyrene and polypropylene. There can also be used metal plates, suchas zinc, and resin treated papers such a melamine resin treated paper,polystyrene treated paper.

The one necessary property of the oleophilic support is that itrepellwater and absorb ink. The degree .of oleophilicity can bedetermined by standard art-recog-. nized techniques, i.e., measuring thecontact angle, thesolubility, the suction and the like.

The supports illustrated above may, if desired, be subjected to asurface treatment. Examples of such a surface treatment are a coronadischarge treatment, an ultrasonic treatment, a heat treatment, achemical treatment, an ultraviolet irradiation, an oxidation by ozone, alaser irradiation, a high frequency wave irradiation, a blastingtreatment, for instance, toughening by propelling small grains againstthe surface, rubbing with emery paper, brushing and the like.

The hydrophilic image receiving layer in this invention is formed bydispersing physical development nuclei in a medium which will be etchedaway by the action of a silver image in an etch-bleach treatment. Asuitable material to be used as the medium is gelatin. Examples of thematerials to be employed as the physical development nuclei arecolloidal silver, silver sulfide, nickel sulfide, zinc sulfide, sodiumsulfide, colloidal sulfur, thiosinamine, stannous chloride, chloroauricacid and the like. The nuclei materials are typically provided by addinga salt such as nickel salt to a gelatin hydrous solution and thereafteradding, e.g., a sulphide to precipitate the diffusion transfer nuclei.

.Thev mediums to be used for forming the hydrophilic image-receivinglayer and the stripping layer for negative emulsion layer work in thisinvention are hydrophilic colloids or a mixture of such hydrophiliccolloids. Examples of the hydrophilic colloid to be used for thispurpose are gelatin, an-alginate, gum arabic, methyl cellulose,carboxymethyl cellulose, hydroxyethyl cellulose, hydroxyethyl starch,hydroxy propione starch, starch, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, a copolymer of vinylacetate and maleic anhydride, a copolymer of vinyl pyrrolidone andmethacrylic acid, and a copolymer of acrylic acid and methylmethacrylate. Particularly effective materials are, however, gelatin, analginate, and a mixture thereof. It will be apparent to one skilled inthe art that to improve the stripping of a layer the degree ofcrosslinking should be weak since it would be preferred to dissolve thelayer in hot water of a relatively low temperature. For instance, aStripping layer which is, at most, only slightly cross-linked can becoated between the emulsion layer and the hydrophilic image receiving.Of course, the silver image formed by transfer diffusion cannot beaffected by the components of the stripping layer.

The photographic properties, and the etching property of these layersdepend upon the molecular weight, the cross-linking degree and thethickness of the hydrophilic colloid layers. In general, it is preferredthat the cross-linking degree be low and the thickness of the layer beabout 0.l-3 microns.

For making a printing plate using the plate orlightsensitive plate ofthis invention, any known process may be used. That is to say, aprinting plate is obtained by image-exposing the light-sensitive plateof this invention, developing the plate to form a positive silver imagein the image forming layer of the plate and then subjecting thedeveloped plate to an etch-bleach treatment removing the image forminglayer at the portion 16 having the silver image together with thehydrophilic intermediate layer under the silver image portion of theimage-receiving layer. For photographing an original,

an ordinary silver halide photographic emulsion is used. In particular,a light-sensitive material having a diffusion transfer silver halideemulsion layer or a lithographic silver halide emulsion layer ispreferred. The image exposure may be conducted by contact exposure,enlarging exposure, transmission exposure or reflection exposure.

The development of the plate of this invention may be conducted by anyconventional manner, but a lithographic development is suitable in anegative to positive system and a diffusion transfer development or alithographic development is preferred in a positive to positive system(see Japanese patent application Open Public Inspection No. 47339/1973).

The etch-bleach treatment in this invention may also be conducted by aknown manner. 7

In our invention, any photosensitive silver halide emulsion layerscommonly used can be used. The silver halide in this invention may besuitably selected from silver chloride, silver bromide, silver iodide,silver chlorobromide, silver chloroiodide, silver bromoiodide and silverchlorobromoiodide, but from the objects of our invention a silver halidehaving high contrast is preferred, e.g., silver chloride, silver bromideand a high contrast silver bromo salt emulsion. As suitable silverhalide emulsions for the objects of this invention, a lithographicsilver halide emulsion is particularly preferred. There is no overlycritical matter involved in selecting any specific silver halide-bindercombination for use in forming the silver halide emulsion layer used inthe present invention. I

As the binder, gelatin is generally used, but other hydrophilic colloidscan be used if desired, e.g., phthalolated gelatin, other gelatinderivatives, vinyl derivatives such as polyvinyl pyrrolidone, polyvinylalcohol, etc. The silver halide emulsions used in this invention maycontain, if desired, known additives such as sensitizers, sensitizingdyes, antifoggants, hardening agents, surface active agents and thelike.

A relatively high amount of silver halide is preferred with respect tobinder is that the silver halide layer provides an excellent silver saltimage when higher amounts of silver are formed and at the same time withhigher; amounts of silver the silver halide layer is etched easily.Since it is necessary that the unhardened portions of the silver halidebe removable, preferably by dissolving with water at about 40C, noportion of the emulsion layer should be overly hardened. However, when astripping layer is used in combination with the silver halide layer thelayer can be hardened to a degree similar to that of knownphotosensitive negative emulsion layers.

In our invention, printing plates may be prepared from thelight-sensitive plates of this invention by any ordinary method, forexample, first the light-sensitive plate of this invention is exposed toan original and developed to form a silver positive image in the silverhalide emulsion layer orthe image-receiving layer. In the photographicprocessing for forming the silver image in the present invention anyordinary developer containing as a developing agentmonomethyl-paminophenol sulfate, hydroquinone, l-phenyl-3- pyrazolidone,amidole, etc., individually or as mixtures thereof can be used, but fromthe objects of our invention, the use of a lithographic developer or alitho- 17 graphic type diffusion transfer developer is most preferred.

The silver halide emulsion layer of the light-sensitive plate of thisinvention thus developed is preferably, then, processed in anetch-bleach solution to form a lithographic plate. Typical etch-bleachsolutions used in this invention contain an ordinary oxidizing agentsuch as hydrogen peroxide or ammonium peroxide which may contain redprussiate, dichromate, peroxysulfate and the like, an insoluble silversalt forming agent such as chloride ions and a metal ion catalyst suchas copper ions. The etch-bleach solution may contain a gelatin softeningagent such as citric acid or urea.

The oxidizing agents are added in amounts as are used in the prior artto conduct photo-bleaching, and the amount may vary greatly dependingupon the exact oxidizing agent or agents selected. Usually, a minimum of0.35 weight percent is used, though up to 100 weight percent can be usedwith weaker oxidizing agents. For instance, in the case of usinghydrogen peroxide, preferably a l to 3 weight percent solution ofhydrogen perioxide is used. By the processing in the etch-bleachsolution, the silver image is etched and at the same time the gelatin atthe silver image portions is decomposed to finish the etching. Theimportant matter in this case is that the hydrophilic intermediate layerunder the silver image portion also be etched in the processing. Afterthe etch-bleach treatment, the remaining softened colloid layer isremoved by softly rubbing the surface of the plate. Examples ofetch-bleach solutions useful in the practice of this invention areillustrated below. The printing plate thus produced can be used in anyordinary manner.

Com osition exam le 1:

A Cupric chloride (dihydrate) g Citric acid 10 g Water added to make 1liter.

B Ammonium persulfate 120 g Water added to make I liter.

Composition example 2:

A Water 750 cc Cupric chloride 10 g Citric acid 10 Water to make 1 iter.

B Hydrogen peroxide (30% aq. soln.) 1 liter.

In the etch-bleach bath it is preferred to add a material such as acupric salt or acid or material which reacts with silver to form a lowsolubility complex.

Exemplary of such cupric salts are copper chloride, copper bromide,copper nitrate, copper sulfate, copper citrate and the like, all ofwhich are soluble in water. Cupric halides are preferred.

Illustrative of the acids which can be used are organic acids such asacetic, citric, tartaric acid and the like, and inorganic acids such ashydrochloric, nitric, sulfuric acid and the like.

As materials which form a complex of low solubility by reacting withsilver there can be mentioned the halogenides, tartrates and carbonates,with the halogenides being especially effective.

These promoting agents can be used singly or in combination, and theamount added is usually 0.05 to 50% based on the weight of the treatingsolution. Generally speaking, one would avoid a totally saturatedsolution and would have a tendency to add the promoting agents so thatthe total amount of all promoting 18 agents would at most be 50% basedon the weight of the treating solution.

Although substantially non-critical in the sense that one merely selectsa temperature which permits adequate etch-bleaching to proceed, usuallyetch-bleaching is at about 5 to about 40C, more generally 15 to 30C.

The etch-bleaching step is merely conducted for a time sufficient tobleach the silver image, and this will vary depending upon thethickness, temperature selected and oxidizing agents used. Usually, morethan about 5 seconds is required, and it can be said that for themajority of processings the etch-bleaching is conducted in from about 15to about 60 seconds, this being sufficient to permit hydrophilic layerscontaining a silver image to be etched.

The main feature of the plate of this invention for making a printingplate lies in the point that a hydrophilic intermediate layer is formedbetween an elecphilic support and an image-forming layer but, ifnecessary, a known layer such as a protective layer, a stripping layer(which is merely removed by mechanical rubbing), an antihalation layer,etc., may be further formed.

The invention will now be further illustrated by the following examples,but the invention should not be construed as limited to these examples.

EXAMPLE 1 (illustrating Embodiment 1; negative-positive process) Thesurfaces of a polyethylene terephthalate film having a thicknessof 0.18mm were treated in a solution of 400 cc sulfuric acid, 200 cc phosphoricacid, and g potassium bichromate (water added to make 3 liters, filmimmersed in system for 3 minutes at 50C same conditions used in allexamples where called for), an antihalation layer was applied to onesurface, and a solution of an alkali soluble hydrophilic resin havingthe following composition was applied to the opposite side of the filmfollowed by drying for 2 minutes at C. to provide a hydrophilicintermediate layer having a thickness of 0.3 micron.

Maleic anhydride-vinyl acetate (1 l) copolymer Methanol AcetoneMethylene chloride Monochloroacetic acid Chromium sulfate Apanchromatically sensitized high contrast lithographic unhardenablegelatino silver chlorobromide emulsion (containing 70% silver chlorideand 1 mole of silver per kg of the emulsion) was applied to theintermediate layer in a thickness of 4 microns and dried. Furthermore, a1% aqueous gelatin solution was applied to the silver halide emulsionlayer in a thickness of 1 micron as a protective layer and dried toprovide a light-sensitive plate of this invention for making printingplates.

The light-sensitive plate thus prepared was exposed through a colornegative original having continuous gradation using a half tone screen.The exposure was conducted at a distance of 1 meter from the lightsource [Fuji Exposure Lamp (made by Fuji Photo Film Co., Ltd.)] for 2seconds at 18 volts using a red filter [Fuji Filter SC 62 (made by FujiPhoto Film Co., Ltd.)]. Thereafter, the plate was developed for 3 min-19 utes at 20C. in a lithographic developer having the followingcomposition.

Boric acid 7 g Hydroquinone 20 g Para-formaldehyde l g Potassium bromide25 g Potassium hydrogen sulfite 2 g Sodium carbonate (monohydrate) 85 gWater added to make 1 liter.

After washing with water, the plate was immersed for one minute at 20C.in the etch-bleach solution prepared by mixing equal amounts of SolutionI and Solution ll of the following compositions.

Solution 1:

Cupric chloride (dihydrate) 10 g Citric acid 10 g Water added to make 1liter. Solution 11:

3% aqueous solution of hydrogen peroxide.

In the processing, the hydrophilic intermediate layer of the portioncorresponding the silver image portion of the silver halide emulsionlayer had been subjected to the etching action and thus when the surfaceof the plate was rubbed softly in a warm water bath at 30C. the etchedportion of the hydrophilic intermediate layer was removed together withthe silver halide emulsion layer, whereby the oleophilic surface of thesupport was exposedjThus, a cyan separate plate of the original wasobtained.

The cyan separate plate was placed on a Davidson SOO-type offsetprinting machine (made by Davidson & Fairchild Corp.) and 5000 printswere made using a commercial printing ink, A-Set Ink (made by Morohoshilnk K. K. and wetting water, Fuji Pronodupli Solution No. 50 (made byFuji Photo Film Co., Ltd.). Thus, a cyan separate image of the originalwas obtained as high quality printed copies having excellent continuousgradation reproducibility. After the run, no stains or defects wereobserved on the surface of the printing plate and thus the printingplate could be used for further printing.

By repeating the same procedure as above, a magenta separate plate, ayellow separate plate and a black separate plate of the original wereformed, and by using the four separate plates prepared above fourcolorprinted copies of the original were obtained.

EXAMPLE 2 (illustrates Embodiment 2; negative-positive process) Aftertreating the surfaces of a polyethylene terephthalate film having athickness of 0.18 mm with a solution containing sulfuric acid,phosphoric acid, and potassium bichromate (as in Example 1) anantihalation layer was applied to one of the surfaces and a solution ofan alkali-soluble hydrophilic resin having the following composition wasapplied to the opposite surface of the support followed by drying for 2minutes at 120C. to form a hydrophilic intermediate layer having athickness of 0.3 micron.

Maleic anhydride-vinyl acetate (1 l) copolymer ethanol -continuedAcetone 25 g Methylene chloride 20 g Monochloroacetic acid 10 g Chromiumsulfate 0.4 g

A solution of a l 1 copolymer of acrylic acid and methyl methacrylatecontaining a slight amount of chromium sulfate was applied to theintermediate layer and dried to form a negative emulsion stripping layerhaving a thickness of 0.2 micron. Then, a panchromatically sensitizedhigh-contrast lithographic hardenable gelatino silver chlorobromideemulsion silver chloride and 1 mole of silver per kg of the emulsion)was applied to the stripping layer in a thickness of 4 microns anddried. Furthermore, a 1% aqueous gelatin solution was applied as aprotective layer in a thickness of 1 micron and dried. Thus, alight-sensitive plate of this invention for making printing plates wasobtained.

The light-sensitive plate was exposed through a color negative originalusing a half tone screen. The exposure was conducted at a distance of 1meter from a light source [Fuji Exposure Lamp (made by Fuji Photo FilmCo., Ltd.)] for 2 seconds at 18 volts using a red filter [Fuji FilterSC-(made by Fuji Photo Film Co., Ltd.)]. Then, the plate was developedfor 3 minutes at 20C. in a lithographic developer having the followingcomposition:

Boric acid Hydroquinone Potassium bromide Para-formaldehyde Sodiumhydrogen sulfite Sodium carbonate (monohydrate) 8 Water added to makeAfter washing with water, the plate was immersed for 1 minute at 25C. inan etch-bleach solution prepared by mixing equal amounts of Solution land Solution ll having the following compositions.

Solution 1 Cupric chloride (dihydrate) 10 g Citric acid 10 g Water addedto make 1 liter. Solution 11 3% aqueous hydrogen peroxide solution.

By the treatment, the silver halide emulsion layer of the portion havinga silver image and also the hydrophilic intermediate layer and thenegative emulsion stripping layer were subjected to etching at theportions corresponding to the silver image portions of the silver halideemulsion layer, and when the surface of the plate was rubbed softly inwarm water at 30C. the etched portion of the hydrophilic intermediatelayer was removed together with the silver halide emulsion layer and thestripping layer to expose the oleophilic surface of the support film.Thus, a cyan separate plate of the original was obtained.

By following the same procedure as in Example 1 using the cyan separateplate thus obtained, 7000 printed copies were obtained. The prints ofthe cyan separate image of the original had excellent continuousgradation reproducibility and high image quality. Neither stains nordefects were observed on the surface of 21 the printing plate and theprinting plate could be used for further printing. 7

By the same procedure as above, a magenta separate plate, a yellowseparate plate and a black separate plate of the original were produced,and by -using the .four

separate plates thus produced four-color printed copies of the originalwere obtained. r

EXAMPLE 3 (illustrates Embodiment 3, positive-positive process) Maleicanhydride-vinyl acetate (1 l) copolymer Methanol Acetone Methylenechloride Monochloroacetic acid Chromium sulfate 0 n #3852321.) WOQOQUUQOQ Then, a direct positive silver halide emulsion (0.5 mole of silverper kg of the emulsion) was applied to the intermediate layer at athickness of 4 microns and dried. Furthermore, a 1% aqueous gelatinsolution was applied thereto at a thickness of 1 micron and dried toprovide a light-sensitive plate for making printing plates.

The light-sensitive plate thus obtained was exposed through a positiveoriginal for 30 seconds at 18 volts at a distance of 1 meter from thelight source [Fuji Exposure Lamp (made byFuji Photo Film Co.," Ltd.)]using a yellow filter [Fuji Auto Posi Filter (made by Fuji Photo FilmCo., Ltd.)]. The plate was then developed for 3 minutes at 25C. in adeveloper having the following composition to provide a positive silverimage the same as the original: I

Monomethyl-p-aminophenol sulfate Anhydrous sodium sulfite HydroquinoneSodium carbonate (monohydrate) Potassium bromide Water Solution l Cupricchloride (dihydrate) Citric acid 1 Water to make Solution ll 3% aqueoushydrogen peroxide solution.

g l0 g 1 liter.

By this treatment, the emulsion layer of the silver image-having portionand the hydrophilic intermediate layer under the silver image portionwere'subjected to etching, and thus when the surface of the plate waslightly rubbed in warm'water at about 30C. the etched portions of thehydrophilic intermediate layer were removed together with the emulsionlayer to expose the oleophilic surface of the support. The printingplate thus obtained gave 7000 line-image printed copies having goodquality by conducting printing in the same manner as in Example 1. i

- EXAMPLE 4 (illustrates Embodiment 4;

positive-positivev process) After treating the surfaces of apolyethylene terephthalate film having a thickness of 180 microns in, asolution containing sulfuric acid, phosphoric acid, and potassiumbichromate, an antihalation layer was applied to one ofthe surfaces anda solution of an alkalisoluble hydrophilic resin having the followingcomposition was'applied tothe opposite surface of the film followed bydrying for 2 minutes at C. to form a hydrophilic intermediate layerhaving a thickness of 0.3

' micron.

Maleic anhydride-vinyl acetate (1 l)-copolymer 1.3 g

. Methanol 45 g Acetone 25 g Methylene chloride 20 g Monochloroaceticacid 10, g Chromium sulfate 0.4 g

Then, a 0.5% sodium alginate solution containing a slight amount ofchromium sulfate was applied to the intermediate layer and dried to forma stripping layer (for a negative emulsion layer) having a thickness of0.2 micron. Thereafter, a direct positive type hardenable silver halideemulsion, (0.5 mole of silver per kg of the emulsion) was appliedthereto at.a thickness of 4 microns and dried. Furthermore, a 1%aqueousgelatin solution wasapplied to the silver halide emulsion layerat a, thickness of l micron as a protective layer andMoncmethyl-p-aminophenol sulfate Anhydrous sodium sulfite HydroquinoneSodium carbonate (monohydrate) Potassium bromide" Water.adde'd to makeAfter washing with water, the plate was immersed for 1 minute at 259C.in an etch-bleach solution prepared by mixing equal amounts of Solutionland Solution ll having the following compositions:

Solution l Cupric chloride (dihydrate) 10 g Citric acid 10 g Water addedto make 1 liter.

' -continued Solution ll 3% aqueous hydrogen peroxide solution.

\ EXAMPLE 5 (illustrates Embodiment 5;

positive-positive process) After treating the'surfaces of a polyethyleneterephthalate having a thickness of 180 microns with a solutioncontaining sulfuric acid, phosphoric'acid, and potassium bichromate, asolution of an alkali-soluble hydrophilic resin having the followingcomposition was applied to one surface of the film and fried for 2minutes at 120C. to form a hydrophilic intermediate layer having athickness of 0.2 micron:

Maleic anhydride-vinyl acetate (1 l) copolymer 1.3 g Methanol 45 gAcetone 25 g Methylene chloride g Monochloroacetic acid 10 g C hromiumsulfate 0.4 g

1 Then, an aqueous gelatin solution containing physical developmentnuclei having the following composition was applied to the hydrophilicintermediate layer and dried for 60 minutes at 60C. to form ahydrophilic diffusion transfer image receiving layer having a thicknessof 0.5 micron. A plate for making printing plates was thus prepared.

Aqueous gelatin dispersion of nickel gelatin 0.5%

, Gelatin 0.6 g

Water 100 g Aqueous 1% solution of sodium dodecylbenzene sulfonate 0.1 g

Aqueous 1% solution of chromium acetate l2 g The plate for printingplates thus prepared was brought into contact with an image-exposedsilver halide light-sensitive material, and while applying a developerhaving the following composition between the two elements, diffusiontransfer development was conducted for 30 seconds at C.

Monomethyl-p-aminophenol sulfate Anhydrous sodium sulfite HydroquinoneAnhydrous sodium thiosulfate Sodium hydroxide Water added to make Then,the light-sensitive material was separated from the plate .for. printingplates and after washing the plate with water, the plate was immersedfor seconds at 259C. in'an etching solution prepared by mixing equal 5amounts of Solution la and {Solution 11- having the. followingcompositions: i

Solution la Cupric chloride (dihydrate) 10 g Citric acid 10 g Wateradded to make 1 liter.

Solution ll 3% aqueous hydrogen peroxide solution.

By the treatment, the silver imageformed in the image receiving layer ofthe plate was-bleached and at thesame time the silver image portion wasetched.

.' Furthermore, at the same time the hydrophilic intermediate layerunder the silver image portion was etched by the treatment. Thus, whenthe surface of the plate was lightly rubbed with a cotton cloth theetched portion of the hydrophilic intermediate layer was removedtogether with the image receiving layer, and thus the oleophic surfaceof the support was exposed. The printing plate thus obtained gave 5000printed copies having a good quality by printing in the same manner asin Example 1.

EXAMPLE 6 (illustrates Embodiment 6; positive-positive process) Anantihalation layer was appliedto one surface of a polyethyleneterephthalate film having a thickness of 180 microns which had beentreated in a solution containing sulfuric acid, phosphoric acid andpotassium bichromate and a solution of an alkali-soluble hydrophilicresin having the following composition was applied to the oppositesurface of the film followed by drying for 10 minutes at 100C. to forma'hydrophilic intermediate layer having a thickness of 0.3 micron.

Maleic anhydride-vinyl acetate- (1 z 1) copolymer Methanol AcetoneMethylene chloride Monochloroacetic acid V Chromium sulfate To thehydrophilic intermediate layer an aqueous gelatin-gum arabic solutioncontaining physical development nuclei having the following compositionwas applied and dried for 60 minutes at 60C. to form a hydrophilicdiffusion transfer image receiving layer having a thickness of 0.5micron:

Gelatin dispersion of nickel sulfide (same as in Example 5) 0.6 gGelatin 0.3 g Gum arabic 0.3 g Water 100 g Aqueous 1% solution of sodiumdodecylbenzene sulfonate 0.4 g Aqueous 1% solution of chromium acetate12 g On the image receiving layer there was formed a layer of apanchromatic lithographic unhardenable gelatino silver chlorobromideemulsion silver chloride, 1 mole of silver per kg of the emulsion) sothat the dry thickness of the layer became 4 microns.

Furthermore, an aqueous 1% gelatin solution was applied to the silverhalide emulsion layer and dried to form a protective layer having athickness of 1 micron.

The light-sensitive plate for printing plates thus prepared was exposedto a positive original and then developed in a developer having thecomposition same as in Example 5 for 30 seconds at 20C. The emulsionlayer was then removed by washing with water at 30C and then the platewas immersed for 1 minute at 25C in an etch-bleach solution prepared bymixing equal amounts of Solution 1 and Solution 11 having the followingcompositions:

Solutionl Cupric chloride (dihydrate) g Citric acid 10 g Water added tomake 1 liter Solution 11 3% aqueous hydrogen peroxide solution When thesurface of the plate was lightly rubbed weakly with a cotton cloth, theimage-receiving layer and the etched portion of the hydrophilicintermediate layer were removed to expose the oleophilic surface of thesupport.

The printing plate thus produced gave 5000 duplications of good quality.

Maleic anhydride-vinyl acetate (1 l) copolymer 1.3 g Methanol 45 gAcetone 25 g Methylene chloride g Monochloroacetic acid 10 g Chromiumsulfate 0.4 g

To the surface of the intermediate layer there was applied an aqueoussodium alginate solution containing physical development nuclei havingthe following composition and the thus formed layer dried for 60 minutesat 60C to form a hydrophilic diffusion transfer image receiving layerhaving a thickness of 0.5 micron:

Aqueous elatin dispersion of nickel sulfide 0.4 g

nickel sulfide 5 X 10*% gelatin 0.5% Sodium alginate Water Aqueous 1%solution of sodium dodecylbenzene sulfonate Aqueous 1% solution ofchromium acetate moo new To the image receiving layer there was appliedan aqueous 1% hydroxyethyl cellulose solution containing a slight amountof chromium sulfate and the solution dried to form a negative emulsionstripping layer having a thickness of 0.2 micron. Then, apanchromatically sensitized lithographic hardenable gelatin silverchlorobromide emulsion (70% silver chloride, 1 mole of silver per kg ofthe emulsion) was applied thereto at a thickness of 4 microns and dried,and further an aqueous 1% gelatin solution was applied and dried to forma protective layer having a thickness of 1 micron to form alight-sensitive plate for making printing plates.

The light-sensitive plate thus formed was exposed to a color positiveoriginal having continuous gradation using a half tone screen at adistance of 1 meter from the light source [Fuji Exposure Lamp (made byFuji Photo Film Co., Ltd.)] for 2 seconds at 18 volts using a red filter[Fuji Filter SC-62 (made by Fuji Photo Film Co., Ltd.)]. The plate wasthen developed for 30 seconds at 25C in a developer having the followingcomposition:

l-Phenyl-S-pyrazolidone Anhydrous sodium sulfite Hydroquinone Anhydroussodium thiosulfate Sodium hydroxide Water added to make The emulsionlayer was then removed by washing with water at 30C and the plate wasimmersed for 1 minute at 25C in an etch-bleach solution prepared bymixing equal amounts of Solution 1 and Solution 11 having thefollowingcompositions:

Solution 1 Cupric chloride (dihydrate) 10 g Citric acid 10 g Water addedto make 1 liter Composition ll 3% aqueous hydrogen peroxide solution Bythis treatment the image receiving layer of the silver image containingportion and also the stripping layer and the hydrophilic intermediatelayer under the silver image portion were etched, and thus when thesurface of the plate was lightly rubbed with a cotton pad in warm waterat about 30C the etched portions were removed to expose the oleophilicsurface of the support. A cyan separate plate of the original was thusprepared.

The cyan separate plate was place on a Davidson 500 Type Offset Machine(made by Davidson & Fairchild Corp.) and printing of 5000 copies wasconducted using the ink and wetting water as in Example 1. Thus, thecyan image of the original was obtained as the high quality printedcopies having excellent continuous gradation reproducibility. Theprinting plate thus used showed neither stains or defects on the surfacethereof and thus could be used for further printing.

By conducting the same procedure as above, a magenta separate plate, ayellow separate plate and a black separate plate of the original wereprepared, and by utilizing the four color separate plates obtainedabove, 4-color printed copies were obtained.

EXAMPLE 8 Maleic anhydride-vinyl acetate (1 l)copo|ymer 1.3 g Methanol45 g Acetone 25 g -continued Methylene chloride 20 g Monochloroaceticacid g Chromium sulfate 0.4 g

When the procedures of Example 1 to 7 were applied to the intermediatelayer, in each case of Embodiments 1-7 illustrated above 7000 printedcopies of excellent quality were obtained.

EXAMPLE 9 Maleic anhydride-vinyl acetate (1 l) copolymer 1.3 g Methanol45 g Acetone 25 g Methylene chloride g Monochloroacetic acid 10 gChromium sulfate 0.4 g

To the hydrophilic intermediate layer was applied a gelatino silverchlorobromide emulsion (containing 80% silver chloride, 0.8 mole ofsilver per kg of the emulsion), 2 g of mucochloric acid and 30 g ofhydroquinone to provide a dry thickness of 4 microns, and further anaqueous 1% gelatin solution was applied thereto and dried to form aprotective layer having a thickness of 1 micron.

The light-sensitive plate for printing plates was exposed through amicrofilm using an enlarger and then the plate was developed for 15seconds at C in a developer having the following composition:

Anhydrous sodium sulfite 2 Sodium hydroxide 3 Potassium bromide Wateradded to make EXAMPLE 10 Examples 1 to 7 were repeated except that aresin solution having the following composition was used to form thehydrophilicintermediate layer, and in each case 5000 excellent printedcopies were obtained.

Polyvinyl alcohol mixed acetalated by (I) mixed acetal benzaldehyde ofpolyvinyl alcohol and (ll) sodium salt of benzaldehyde- 2-sulfonic acid(I: 25%, ll: 45%,

and -OH Methanol Acetone Benz l alcohol o-Ch orophenol EXAMPLE 1 1Examples 1 to 7 were repeated except that a resin solution having thefollowing composition was used to 28 form the hydrophilic intermediatelayer. 5000 excellent printed copies were obtained in each case.

Copolymer of 66% diethyl acrylamide and 34% methacrylic acid MethanolAcetone Methylene chloride o-Chlorophenol Chromium acetate EXAMPLE 12Examples 1 to 7 were repeated except that a resin solution having thefollowing composition was used to form the hydrophilic intermediatelayer. 500 excellent printed copies were obtained in each case:

Maleic anhydride-methyl vinyl ether (1 l) copolymer l.5 g Methanol 45 gAcetone 25 g Methylene chloride 23 g Resorcinol 10 g Chromium acetate0.5 g

EXAMPLE 13 Examples 1 to 7 were repeated except that a resin solutionhaving the following composition was used to form the hydrophilicintermediate layer. 5000 excellent printed copies were obtained in eachcase:

Examples 1 to 7 were repeated except that a resin solution having thefollowing composition was used to form the hydrophilic intermediatelayer. 5000 excellent printed copies were obtained in each case:

Hydroxyethyl cellulose 1.5 g Water 1 g Acetic acid 1 g Phenol 5 gTetrachloroethane 20 g Methanol 40 g Methylene chloride 10 g Acetone 60g EXAMPLE 15 Examples 1 to 7 were repeated except that a resin solutionhaving the following composition was used to form the hydrophilicintermediate layer. 5000 excellent printed copies were obtained in eachcase:

Polyvinyl pyrrolidone-polyvinyl alcohol (6 4) copolymer Water Salicylicacid Methanol Acetone Formalin Resorcinol ulutp meoOOm&N oeunonoeonoetn-continued COMPARISON EXAMPLES 1-3 X I A plate for making printingplates or a light-sensitive plate for makingprinting plates was preparedas in Examples 5-7 except that no hydrophilic intermediate layer wasformed, that is to say, the plate for printing plates was produced bycoating a polyethylene terephthalate film subjected to a surfacetreatment with an aqueous gelatin solution containing physicaldevelopment nuclei and drying for minutes at 120C to form hydrophilicdiffusion transfer image receiving layer having a thickness of 0.3micron. The plates thus produced were exposed and developed as inExamples 5-7. However, when the negative materials were separated fromthe developed plates the hydrophilic diffusion transfer image receivinglayers were also stripped from the polyethylene terephthalate film s,and thus the plates could not be used as printing plates.

COMPARISON EXAMPLES 4-6 Polyester 0.7 g Nitrocellulose l .0 g Ethylenedichloride 150.0 g Acetone 50.0 g Methanol l 3 .0 g Tetrachloroethane l5.0 g

The polyester was prepared by reacting a mixture of 1 mole of dimethylterephthalate, 1.5 moles of ethylene glycol. and 1 mole of triethyleneglycol.

An aqueous gelatin solution containing physical development nuclei (thesame as was used in Examples 5-7) was applied to the surface of theintermediate layer and dried for 60 minutes at 60C to form a hydrophilicdiffusion transfer image receiving layer having a thickness of 0.5micron. The plate for printing plates thus produced was exposed anddeveloped in the same manner as in Examples 5-7. In the printing platethus prepared the intermediate layer had not been sufficiently etchedand thus printing ink did not attach to the image portions, which madeit impossible to use the printing plate for printing.

From the above comparison examples, the remarkable merits of thehydrophilic intermediate layers formed according to the presentinvention will be well understood.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:

l. A method of making a lithographic printing plate from a platecomprising a support having an oleophilic surface bearing thereon ahydrophilic intermediate layer containing at least one compound selectedfrom the following groups A, B and C:

Group A: gum arabic, alginic acid, hydroxyethyl cellulose, methylcellulose, carboxymethyl cellulose, polyacrylamide, polyvinylpyrrolidone, co-

polymers of the above components, polyvinyl alcohol, and apolyvinylalcohol derivative;

Group B: a maleic anhydride-vinyl acetate copolymer, a maleic Ianhydride-ethylene copolymer, a maleic anhydride-methyl vinylethercopolymer, a maleic anhydride-styrene copolymer, half ester derivativesof those copolymers, half amide derivatives of those copolymers, anacrylic acid copolymer, and a methacrylic acid copolymer; and

Group C: partially saponified cellulose acetate, partially saponifiedcellulose butyrate, and partially saponified cellulose acetate butyrate;

said intermediate layer bearing thereon a photosensitive silver halideemulsion layer a; or

a hydrophilic diffusion transfer image receiving layer (b) containingphysical development nuclei, or

a layer b carrying thereon a silver halide emulsion layer a on the sidethereof away from the hydrophilic intermediate layer, which methodcomprises:

forming a silver image in layer a or b,

removing layer a when it is present on layer b, and

etch bleaching the silver image, thereby etching away layer a or b atsilver image portions thereof and at the same time the hydrophilicintermediate layer under the silver image portions thereof to therebyexpose the oleophilic surface of the support at portions correspondingto the silver image portions in layer a or b.

2. A method as claimed in claim 1, wherein the degree of saponificationof the materials of Group C is less than 2%.

3. A method as claimed in claim 1, where the photosensitive silverhalide emulsion layer has a thickness of from 1 to 15 microns.

4. A method as claimed in claim 1, wherein the photosensitive silverhalide emulsion layer comprising at least one silver halide and a binderpresent at a ratio of from l/4 to 6/1.

5. A method as claimed in claim 1, wherein the hydrophilic diffusiontransfer image receiving layer has a thickness of from 0.1 to 3 microns.

6. A method as claimed in claim 5, wherein the hydrophilic diffusiontransfer image receiving layer comprises physical development nuclei anda binder, the ratio of nuclei/binder being from 0.1/1 to 0.001/1.

7. A method as claimed in claim 1, wherein said plate further comprisesa stripping layer between the photosensitive silver halide emulsionlayer and a layer thereunder.

8. A method as claimed in claim 1, wherein both the photosensitivesilver halide emulsion layer and the hydrophilic diffusion transferimage receiving layer are present.

9. A method as claimed in claim 1, wherein the compound is selected fromGroup A.

10. A method as claimed in claim 1, wherein the compound is selectedfrom Group B.

11. A method as claimed in claim 1, wherein the compound is selectedfrom Group C.

12. A method as claimed in claim 1 where said hydrophilic intermediatelayer is substantially free of physical development nuclei.

13. A plate as claimed in claim 1 where said hydrophilic intermediatelayer is substantially free of physical development nuclei.

14. A method as claimed in claim 1, wherein the hydrophilic diffusiontransfer image receiving layer 31 containing physical development nucleihas a thickness of from 0,1 to 3 microns, wherein the hydrophilicintermediate layer has a thickness of from 0.1 to 3 microns, whereintheamount of silver formed in the image receiving layer (b) is greater than0.3 in optical density, 5

wherein the thickness of the silver halide-emulsion layer is from aboutl to about microns, wherein the weight ratio of silver halide to binderof the emulsion layer is in the range of about 1/4 to 6/1, wherein the

1. A METHOD OF MAKING A LITHOGRAPHIC PRINTING PLATE FROM A PLATECOMPRISING A SUPPORT HAVING AN OLEPHILIC SURFACE BEARING THEREON AHYDROPHILIC INTERMEDIATE LAYER CONTAINING AT LEAST ONE COMPOUND SELECTEDFROM THE FOLLOWING GROUPS A, B AND C: GROUP A: GUM ARABIC, ALGINIC ACID,HYDROXYETHYL CELLULOSE, METHYL CELLULOSE, CARBOXYMETHYL CELLULOSE,POLYACRYLAMIDE, POLYVINYL PYRROLIDONE, COPOLYMERS OF THE ABOVECOMPONENTS, POLYVINYL ALCOHOL, AND A POLYVINYL ALCOHOL DERIVATIVE; GROUPB: A MALEIC ANHYDRIDE-VINYL ACETATE COPOLYMER, A MALE;ICANHYDRIDE-ETHYLENE COPOLYMER, A MALEIC ANHYDRIDE-METHYL VINYLETHERCOPOLYMER, A MALEIC ANHYDRIDESTYRENE COPOLYMER, HALG ESTER DERIVATIVESOF THOSE COPOLYMERS, HALF AMIDE DERIVATIVES OF THOSE COPOLYMERS, ANACRYLIC ACID COPOLYMER, AND A METHACRYLIC ACID COPOLYMER; AND GROUP C:PARTIALLY SAPONIFIED CELLULOSE ACETATE, PARTIALLY SAPONIFIED CELLULOSEBUTYRATE, AND PARTIALLY SAPONIFIED CELLULOSE ACETATE BUTYRATE; SAIDINTERMEDIATE LAYER BEARING THEREON A PHOTOSENSITIVE SILVER HALIDEEMULSION LAYER A; OR A HYDROPHILIC DIFFUSION TRANSFER IMAGE RECEIVINGLAYER (B) CONTAINING PHYSICAL DEVELOPMENT NUCLEI, OR A LAYER B CARRYINGTHEREON A SILVER HALIDE EMULSION LAYER A'' ON THE SIDE THEREOF AWAY FROMTHE HYDROPHILIC INTERMEDIATE LAYER, WHICH METHOD COMPRISES: FORMING ASILVER IMAE IN LAYER A OR B, REMOVING LAYER AZ WHEN IT IS PRESENT ONLAYER B, AND ETCH BLEACHING THE SILVER IMAGE, THEREBY ETCHING AWAY LAYERA OR B AT SILVER IMAGE PORTIONS THEREOF AND AT THE SAME TIME THEHYDROPHILIC INTERMEDIATE LAYER UNDER THE SILVER IMAGE PORTIONS THEREOFTO THEREBY EXPOSE THE OLEOPHILIC SURFACE OF THE SUPPORT AT PORTIONSCORRESPONDING TO THE SILVER IMAGE PORTIONS IN LAYER A OR B.
 2. A methodas claimed in claim 1, wherein the degree of saponification of thematerials of Group C is less than 2%.
 3. A method as claimed in claim 1,where the photosensitive silver halide emulsion layer has a thickness offrom 1 to 15 microns.
 4. A method as claimed in claim 1, wherein thephotosensitive silver halide emulsion layer comprising at least onesilver halide and a binder present at a ratio of from 1/4 to 6/1.
 5. Amethod as claimed in claim 1, wherein the hydrophilic diffusion transferimage receiving layer has a thickness of from 0.1 to 3 microns.
 6. Amethod as claimed in claim 5, wherein the hydrophilic diffusion transferimage receiving layer comprises physical development nuclei and abinder, the ratio of nuclei/binder being from 0.1/1 to 0.001/1.
 7. Amethod as claimed in claim 1, wherein said plate further comprises astripping layer between the photosensitive silver halide emulsion layerand a layer thereunder.
 8. A method as claimed in claim 1, wherein boththe photosensitive silver halide emulsion layer and the hydrophilicdiffusion transfer image receiving layer are present.
 9. A method asclaimed in claim 1, wherein the compound is selected from Group A.
 10. Amethod as claimed in claim 1, wherein the compound is selected fromGroup B.
 11. A method as claimed in claim 1, wherein the compound isselected from Group C.
 12. A method as claimed in claim 1 where saidhydrophilic intermediate layer is substantially free of physicaldevelopment nuclei.
 13. A plate as claimed in claim 1 where saidhydrophilic intermediate layer is substantially free of physicaldevelopment nuclei.
 14. A method as claimed in claim 1, wherein thehydrophilic diffusion transfer image receiving layer containing physicaldevelopment nuclei has a thickness of from 0.1 to 3 microns, wherein thehydrophilic intermediate layer has a thickness of from 0.1 to 3 microns,wherein the amount of silver formed in the image receiving layer (b) isgreater than 0.3 in optical density, wherein the thickness of the silverhalide emulsion layer is from about 1 to about 15 microns, wherein theweight ratio of silver halide to binder of the emulsion layer is in therange of about 1/4 to 6/1, wherein the amount of silver of the silverhalide in the emulsion layer is from about 5 to about 60 mg/dm2, whereinthe weight ratio of nuclei to binder of the image receiving layer (b) isfrom about 0.1/1 to about 0.001/1 and the total nuclei content is atleast about 0.001 mg/dm2, and wherein the hardenability of thehydrophilic intermediate layer is such that it can be etched by means ofan etch-bleach bath.